Nanoshape patterning techniques that allow high-speed and low-cost fabrication of nanoshape structures

ABSTRACT

A method for template fabrication of ultra-precise nanoscale shapes. Structures with a smooth shape (e.g., circular cross-section pillars) are formed on a substrate using electron beam lithography. The structures are subject to an atomic layer deposition of a dielectric interleaved with a deposition of a conductive film leading to nanoscale sharp shapes with features that exceed electron beam resolution capability of sub-10 nm resolution. A resist imprint of the nanoscale sharp shapes is performed using J-FIL. The nanoscale sharp shapes are etched into underlying functional films on the substrate forming a nansohaped template with nanoscale sharp shapes that include sharp corners and/or ultra-small gaps. In this manner, sharp shapes can be retained at the nanoscale level. Furthermore, in this manner, imprint based shape control for novel shapes beyond elementary nanoscale structures, such as dots and lines, can occur at the nanoscale level.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is related to the following commonly owned U.S. patentapplication:

Provisional Application Ser. No. 62/067,496, “Precise Nanoscale ShapeControlled Large Area Patterning,” filed Oct. 23, 2014, and claims thebenefit of its earlier filing date under 35 U.S.C. § 119(e).

GOVERNMENT INTERESTS

This invention was made with government support under Grant No. EEC1160494 and Grant No. ECCS1120823 awarded by the National ScienceFoundation. The U.S. government has certain rights in the invention.

TECHNICAL FIELD

The present invention relates generally to fabrication ofnanostructures, and more particularly to nanoshape patterning techniquesthat allow high-speed and low-cost fabrication of nanoshape structures.

BACKGROUND

In a variety of nano-device applications, high-speed (low-cost)fabrication of nanostructures with sharp shapes is important. Thisincludes devices exploiting nanoscale phenomena in optics, magnetics andbiomedical materials. Specific device applications where these types ofstructures are needed are discussed below.

In the area of nanophotonics, the following exemplary shaped structuresshown in FIGS. 1A and 1B are desirable. FIGS. 1A and 1B illustratestructures 101, 102, respectively, where the gaps g1 and g2 can be assmall as 2 nm, and points A and B (see FIG. 1A) are sharp corners with aradius of curvature as small as 1 nm.

In the area of magnetics, multi-bit magnetic random access memory can beachieved using exemplary structures as shown in FIG. 2A, where d1 may be<10 nm in size. Similarly for thin-film heads used to read and writedata onto hard disk drives, the following shaped structures as shown inFIG. 2B are desirable, where d2 may be <10 nm.

In the biomedical area, the ability to make shape controllednanoparticles are known to be of interest in targeted diagnostics anddrug delivery.

Currently, the highest resolution large area nanopatterning is used tomake non-volatile CMOS based memory, specifically NAND flash with 17 nmhalf pitch and bit patterned media for high density magnetic storage inhard disks. While this patterning has historically been performed byphotolithography, the resolution of the most advanced form ofphotolithography—193 nm immersion (193i) lithography—has plateaued at aresolution of approximately 40 nm halfpitch. Higher resolution patternsare fabricated by self-aligned double patterning (SADP), extremeultraviolet lithography (EUVL), and multiple e-beam lithography (MEBL),but these techniques suffer from high costs, low throughput and arerestricted to patterning periodic features.

Unfortunately, nanoimprinting techniques are currently limited tofabricating elementary nanoscale structures, such as dots, lines, etc.Current nanoimprinting techniques do not possess shape control to allowit to create nanoscale patterns with complex shapes which could be usedin a variety of areas, such as magnetic memory, nanophotonic devicesbased on plasmonic and metamaterial structures and biomedicalapplications.

BRIEF SUMMARY

In one embodiment of the present invention, a method for templatefabrication of ultra-precise nanoscale shapes comprises formingstructures with a smooth shape on a substrate using lithography. Themethod further comprises subjecting the structures to an atomic layerdeposition of one or more films leading to nanoscale sharp shapes withfeatures that exceed lithography resolution capability of sub-10 nmresolution. The method additionally comprises performing a resistimprint of the nanoscale sharp shapes using imprint lithography.Furthermore, the method comprises etching the nanoscale sharp shapesinto underlying functional films on the substrate forming a nanoshapedtemplate with nanoscale sharp shapes that comprise one or more of thefollowing: sharp corners and ultra-small gaps ranging from 1 to 10nanometers.

In another embodiment of the present invention, a method for templatereplication of ultra-precise nanoscale shapes comprises using a mastertemplate for patterning of imprint material on a residual layer that ispositioned on a dissolvable layer which is positioned on a substrate.The method further comprises depositing a dielectric layer over theimprint material and the residual layer to capture shape details. Themethod additionally comprises performing one of chemical vapordeposition, physical vapor deposition and atomic layer deposition of thedeposited dielectric layer to create a film over the imprint materialand the residual layer. Furthermore, the method comprises planarizingthe film. Additionally, the method comprises bonding a replica substrateonto the planarized film. In addition, the method comprises eliminatingthe dissolvable layer followed by flipping over a structure comprisingthe imprint material, the residual layer and the substrate. Furthermore,the method comprises removing the imprint material thereby forming areplica template.

In a further embodiment of the present invention, a method for etchingultra-precise nanoscale shapes comprises depositing a dielectric layerover imprint material comprised of inorganic material and a residuallayer that is positioned on a functional film layer which is positionedon a substrate. The method further comprises performing a planarizationof the dielectric layer. The method additionally comprises etching backthe planarized dielectric layer, wherein the imprint material ispre-compensated to account for system degradation of shape during theetching. Furthermore, the method comprises creating a negative patternof the imprint material after removing the imprint material.

In another embodiment of the present invention, a method to fabricateshaped cross-section silicon nanowires comprises depositing asacrificial polymeric layer on a silicon. The method further comprisesimprinting on the sacrificial polymeric layer using a nanoscale shapedtemplate. The method additionally comprises etching a polymeric residuallayer resulting from the imprinting. Furthermore, the method comprisesetching an underlying sacrificial polymeric layer following the etchingof the polymeric residual layer, wherein the underlying sacrificialpolymeric layer etch results in an undercut. Additionally, the methodcomprises performing a physical vapor deposition of a noble metal. Inaddition, the method comprises removing the sacrificial polymeric layerto create nanoshaped noble metal structures on the silicon. Furthermore,the method comprises performing a metal assisted chemical etchingprocess to create nanowires.

In a further embodiment of the present invention, a method to fabricateshaped cross-section silicon nanowires comprises depositing asacrificial polymeric layer on a silicon. The method further comprisesimprinting on the sacrificial polymeric layer using a nanoscale shapedtemplate. The method additionally comprises coating the sacrificialpolymeric layer with a silicon organic coating. Furthermore, the methodcomprises planarizing and etching the silicon organic coating in aplasma involving fluorine and oxygen. Additionally, the method comprisesetching an underlying sacrificial polymeric layer, wherein theunderlying sacrificial polymeric layer etch results in an undercut. Inaddition, the method comprises performing a physical vapor deposition ofa metal to promote adhesion. The method further comprises performing aphysical vapor deposition of a noble metal. The method additionallycomprises removing the sacrificial polymeric layer to create nanoshapednoble metal structures on the silicon. Furthermore, the method comprisesperforming a metal assisted chemical etching process to createnanowires.

The foregoing has outlined rather generally the features and technicaladvantages of one or more embodiments of the present invention in orderthat the detailed description of the present invention that follows maybe better understood. Additional features and advantages of the presentinvention will be described hereinafter which may form the subject ofthe claims of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

A better understanding of the present invention can be obtained when thefollowing detailed description is considered in conjunction with thefollowing drawings, in which:

FIGS. 1A and 1B illustrates desirable shaped structures in the area ofnanophotonics;

FIG. 2A illustrates an exemplary structure in the area of magnetics toachieve multi-bit magnetic random access memory;

FIG. 2B illustrates desirable shaped structures for thin-film heads usedto read and write data onto hard disk drives;

FIG. 3 is a flowchart of a method for using imprint lithography topattern nanoscale shapes in accordance with an embodiment of the presentinvention;

FIGS. 4A-4D depict cross-sectional views of patterning nanoscale shapesusing the steps described in FIG. 3 in accordance with an embodiment ofthe present invention;

FIG. 5 is a flowchart of a method for fabricating a template inaccordance with an embodiment of the present invention;

FIGS. 6A-6D depict cross-sectional views of fabricating a template usingthe steps described in FIG. 5 in accordance with an embodiment of thepresent invention;

FIG. 7 is scanning electron microscope (SEM) micrographs of theresulting nanoshaped template using the method of FIG. 5 in accordancewith an embodiment of the present invention;

FIG. 8A is an SEM image of the template showing a 2.6 nm radius cornerin accordance with an embodiment of the present invention;

FIG. 8B is an SEM image of the imprint resist before the residual layeretch in accordance with an embodiment of the present invention;

FIG. 8C is an SEM image of the etched diamond showing 5.2 nm radiuscorners in the oxide in accordance with an embodiment of the presentinvention;

FIG. 8D is an SEM image of the diamond shaped nanowire cross-section inaccordance with an embodiment of the present invention;

FIG. 8E is an SEM image of the high aspect ratio shaped siliconnanowires in accordance with an embodiment of the present invention;

FIG. 8F is an SEM image of the circular silicon nanowires in accordancewith an embodiment of the present invention;

FIG. 9A illustrates a circular cross section capacitor in accordancewith an embodiment of the present invention;

FIG. 9B illustrates a diamond cross section capacitor model inaccordance with an embodiment of the present invention;

FIG. 10 is a flowchart of a method for retaining the detailed shapes ofan imprinted feature while creating a replica without the use of areactive ion etch (RIE) process in accordance with an embodiment of thepresent invention;

FIGS. 11A-11F depict cross-sectional views of fabricating a replicatemplate using the steps described in FIG. 10 in accordance with anembodiment of the present invention;

FIG. 12A is a scanning electron microscope (SEM) image of apre-compensated template in accordance with an embodiment of the presentinvention;

FIG. 12B is an SEM image of the imprinted feature with a nanoscalebridge in accordance with an embodiment of the present invention;

FIG. 12C is an SEM image of the post-etch pattern with separateddiamond-like shapes in accordance with an embodiment of the presentinvention;

FIG. 13 is a flowchart of method for creating a negative replica of theimprinted image in a dielectric in accordance with an embodiment of thepresent invention;

FIGS. 14A-14D depict cross-sectional views of creating a negativereplica of the imprinted image in a dielectric using the steps describedin FIG. 13 in accordance with an embodiment of the present invention;

FIG. 15 is a flowchart of a method for performing a bi-layer lift-offusing a template that prints holes in the resist in accordance with anembodiment of the present invention;

FIGS. 16A-16D depict cross-sectional views of performing a bi-layerlift-off using a template that prints holes in the resist using thesteps described in FIG. 15 in accordance with an embodiment of thepresent invention;

FIG. 17 is a flowchart of a method for performing a reverse tonebi-layer lift-off process with resist pillars as opposed to holes inaccordance with an embodiment of the present invention;

FIGS. 18A-18D depict cross-sectional views of performing a reverse tonebi-layer lift-off process with resist pillars using the steps describedin FIG. 17 in accordance with an embodiment of the present invention;

FIG. 19 is a flowchart of a method for performing a simplified bi-layerlift-off process in accordance with an embodiment of the presentinvention;

FIGS. 20A-20D depict cross-sectional views of performing a simplifiedbi-layer lift-off process using the steps described in FIG. 19 inaccordance with an embodiment of the present invention;

FIG. 21 illustrates the gold mesh with circular holes created using themethod of FIG. 19 in accordance with an embodiment of the presentinvention;

FIG. 22A illustrates the top down SEM of the pillars etched using thesimplified circular mesh in accordance with an embodiment of the presentinvention;

FIG. 22B illustrates the cross-section of the SEM of the pillars etchedusing the simplified circular mesh in accordance with an embodiment ofthe present invention;

FIG. 23 illustrates the gold mesh with diamond holes created using themethod of FIG. 19 in accordance with an embodiment of the presentinvention;

FIG. 24A illustrates the top down SEM of the pillars etched using thesimplified diamond mesh in accordance with an embodiment of the presentinvention;

FIG. 24B illustrates the cross-section of the SEM of the pillars etchedusing the simplified diamond mesh in accordance with an embodiment ofthe present invention;

FIG. 25 is a flowchart of a method for fabricating an ultra-capacitorfrom nanowires in accordance with an embodiment of the presentinvention; and

FIGS. 26A-26E depict cross-sectional views of fabricating anultra-capacitor from nanowires using the steps described in FIG. 25 inaccordance with an embodiment of the present invention.

DETAILED DESCRIPTION

The present invention focuses on using imprint lithography to patternnanoscale shapes. An exemplary imprint lithography technique, known asJet and Flash Imprint Lithography (J-FIL) is described next. A uniquefeature of J-FIL is that it uses a targeted resist dispense approachthat allows adaptive material deposition to match pattern densityvariations in the mask that is to be replicated. This combined with lowviscosity resist formulations leads to high throughput processes. Aprocess for using imprint lithography to pattern nanoscale shapes isdiscussed below in connection with FIGS. 3 and 4A-4D. FIG. 3 is aflowchart of a method 300 for using imprint lithography to patternnanoscale shapes in accordance with an embodiment of the presentinvention. FIG. 3 will be discussed in conjunction with FIGS. 4A-4D,which depict cross-sectional views of patterning nanoscale shapes usingthe steps described in FIG. 3 in accordance with an embodiment of thepresent invention.

Referring to FIG. 3, in step 301, the UV curable monomer resist liquid401 is dispensed on a surface 402 of the wafer 403 by an inkjetdispenser 404 as shown in FIG. 4A.

In step 302, the amount of resist dispensed is tailored according to thevolume of the features 404 on the template 405 as shown in FIG. 4B.

In step 303, the patterned region of the mask 405 called the field (seefeatures 404) is brought in contact with the liquid drops 401 so thatthe resist fills the etched regions of the mask 405 by capillary actionas shown in FIG. 4C. The largest monomer molecule in the resist used inthis study is estimated to be about 1 nm by approximating a linearbackbone.

In step 304, the resist is then polymerized by UV radiation 406 by ablanket cure step as shown in FIG. 4C.

In step 305, the mask 405 is separated from the wafer leaving theopposite tone of the mask pattern in the resist 401 as shown in FIG. 4D.

Imprinting time of less than 2 s is made possible by dispensing a gridcontaining thousands of drops with drop volumes of 6 picoliters or lessand advanced drop layout optimization. J-FIL has demonstrated 24 nmpatterning with <2 nm line edge roughness and 1.2 nm critical dimensionuniformity. Due to its molecular level resolution, it is a viablecandidate for manufacturing high precision devices requiringunconventional nanoshape geometries.

The principles of the present invention address novel templatefabrication techniques, integration of materials to enable in-situmetrology of template and patterning materials, and novel methods forretention of desired shape through patterning and pattern transferprocesses.

Shape controlled template fabrication has been previously discussed withrespect to polygonal shape. The present invention discloses the conceptof creating sharp nanoshapes by starting from smooth shapes, such ascircular or elliptical cross-section pillars, and using preciseconformal deposition using techniques, such as chemical vapor deposition(CVD) or atomic layer deposition (ALD). FIG. 5 is a flowchart of amethod 500 for fabricating a template in accordance with an embodimentof the present invention. FIG. 5 will be discussed in conjunction withFIGS. 6A-6D, which depict cross-sectional views of fabricating atemplate using the steps described in FIG. 5 in accordance with anembodiment of the present invention.

Referring to FIG. 5, in step 501, structures 601 with a smooth shape(e.g., circular or elliptical cross-section pillars) are formed on asubstrate 602 (e.g., fused silica substrate) using electron beamlithography as shown in FIG. 6A.

In step 502, structures 601 are subject to atomic layer deposition (ALD)of a dielectric (e.g., silicon dioxide) interviewed with a deposition ofa conductive film (e.g., TiN) leading to nanoscale sharp shapes 603(e.g., diamond-like shapes) with features that exceed electron beamresolution capability of sub-10 nm resolution as shown in FIG. 6B.

In step 503, a resist imprint 604 of these nanoscale sharp shapes 603using J-FIL is performed as shown in FIG. 6C.

In step 504, nanoscale sharp shapes 603 are etched into underlyingfunctional films (e.g., thermal oxide) on silicon wafer 602 forming ananoshaped template 605 with nanoscale sharp shapes that include sharpcorners and/or ultra-small gaps ranging from 1 to 10 nm. In oneembodiment, nanoshaped template 605 is pre-compensated (such as using ananoscale bridge that connects adjacent nanoscale sharp shapes) toaccount for system degradation of the shape during the etching step asdiscussed further below. In one embodiment, such a nanoshaped template605 with nanoscale sharp shapes may be utilized in various applications,such as magnetic memory, nanophotonic devices and biomedicalapplications. SEM micrographs of the resulting nanoshaped template 605are shown in FIG. 7 in accordance with an embodiment of the presentinvention.

FIGS. 5 and 6A-6D illustrate the process flow for creating templateswith diamond-like shapes that include sharp corners starting fromcircular cross-section pillars. The data included in FIGS. 5 and 6A-6Dwas obtained using ALD of SiO₂ interleaved with ALD of TiN. TiN filmsare reasonably conductive and reasonably transparent to UV light atabout 20 nm (UV transparency is needed for crosslinking exposure inJ-FIL). SiO₂ is desired as the final film as imprint process materialstypically are compatible with SiO₂. A nanoshaped template created inthis manner with embedded TiN can be inspected under an SEM withoutcharging effects as TiN is conducting. This approach can be used tocreate templates with very precise nanoscale control.

SEM inspection can be carried out in-situ and additional deposition canbe carried out to create and refine a template that has the desirednanoshape geometry. In a situation where a very small feature isrequired (such as the ones in FIGS. 1A and 1B), or where the size offeatures has to be adjusted without compromising sharp shapes (FIGS. 2Aand 2B), this approach of nanoscale deposition with in-situ metrologycapability can be very useful. It is important to ensure in thesesituations that the starting features are precise in their size, shapeand location. For example, the pillar features in FIGS. 6A-6D need tohave a diameter control, and placement control of sub-3 nm. Also, thepillar wall angle should be substantially vertical (as close to 90° aspossible). Very precise size and placement control can be possible usingcombinations of electron beam wherein the feature pitch is preciselycontrolled along with techniques, such as block copolymer (BCP) directedself-assembly (DSA). BCP can provide precise size control and DSA canensure precise location control relative to the electron beam grid. Sidewall angle control can be improved by embedding an etch stop underneaththe patterning material during the creation of the pattern prior todeposition, such as ALD. For example, the SiO₂ pillars shown in FIGS.6A-6D can be created on top of a SiN layer that can be used as an etchstop during the SiO₂ anisotropic reactive ion etch (RIE) to create thepillars. Such as etch stop allows for a modest over-etch in theanisotropic RIE step to ensure that the wall angles are substantiallyvertical.

Finally, the diamond template is used to form shaped nanowires withsharp corners to produce large arrays of diamond-shaped nanowires, whichcan be used as enhanced capacitors. (Here the diamond shape has beenused as an exemplary shape to form nanoshaped cross-section nanowires.Other nanoscale shapes can also be used to make similar nanowires, suchas cross-sectional shapes disclosed in U.S. Pat. No. 8,828,297, which ishereby incorporated by reference in its entirety.) Here the template inFIGS. 6A-6D is used to form a diamond pattern with gold followed by ametal assisted chemical etching (MACE) process (discussed below) used tocreate the shaped silicon nanowires. Images of the diamond nanowires areshown in FIGS. 8A-F. FIG. 8A is an SEM image of the template showing a2.6 nm radius corner in accordance with an embodiment of the presentinvention. FIG. 8B is an SEM image of the imprint resist before theresidual layer etch in accordance with an embodiment of the presentinvention. FIG. 8C is an SEM image of the etched diamond showing 5.2 nmradius corners in the oxide in accordance with an embodiment of thepresent invention. FIG. 8D is an SEM image of the diamond shapednanowire cross-section in accordance with an embodiment of the presentinvention. FIG. 8E is an SEM image of the high aspect ratio shapedsilicon nanowires in accordance with an embodiment of the presentinvention. FIG. 8F is an SEM image of the circular silicon nanowires inaccordance with an embodiment of the present invention.

Furthermore, capacitors were fabricated using these diamond-shapednanowires (discussed below). The diamond-shaped nanowires havesignificantly improved capacitance compared to circular Si nanowirecapacitors

Equation (1) (shown further below) gives the capacitance of acylindrical capacitor which is a function of its height (h) and theinner (a) and outer (b) radii of the dielectric ring as shown in FIGS.9A-9B. FIG. 9A illustrates a circular cross section capacitor 900, wherea is the radius of the inner electrode 901 and b is the radius of theouter electrode 902 in accordance with an embodiment of the presentinvention. FIG. 9B illustrates a diamond cross section capacitor model903 with equivalent a and b in accordance with an embodiment of thepresent invention.

The equation accounts for the difference in surface area due to thedielectric thickness. For the capacitors with circular cross section, ais 50 nm, and b is 61 nm. In one embodiment, the dielectric constantused in the analytical calculations was back calculated using theparallel plate capacitor equation and data from a capacitor with knownthicknesses. This was done because the method of deposition caninfluence the actual dielectric constant value compared to theoreticalvalues. In the case of the diamond cross section shown in FIG. 8B, thecalculations were performed using the titanium nitride electrodes whichare assumed to be pillars with circular cross sections of 100 nm radius.The projected increase in capacitance for a diamond cross sectioncompared to the circular cross section for the same projected area andpillar height was calculated to be ˜76%.

$\begin{matrix}{C_{cylinder} = \frac{2{\pi ɛ}_{0}ɛ_{S}h}{\ln( {b/a} )}} & (1)\end{matrix}$

The capacitance of the nanowires is 18.44 nF/cm²/nm compared to 9.67nF/cm²/nm for circular nano-wire capacitors which is a 90.62% increasein capacitance per projected area per unit pillar height as shown inTable 1. The experimental capacitance values were slightly less than theexpected analytic values which are believed to be due to some criticaldimension loss compared to the ideal geometries during pattern transfer.The nanowire capacitor data has been normalized not only for a unitsquare area but also for a unit height of the nanowires to alloweffective comparison with other similar work reported in literature. Theresulting shaped nanowire capacitors not only exceeded the circularnanowire capacitor, but also porous nanocapacitors previously reportedwhere they achieved ˜10 nF/cm²/nm. Further, the approach of the presentinvention should be scalable to 10× smaller half-pitch nanowires sincenanoimprint has demonstrated structures as small as 10 nm half-pitchover large areas; this would increase surface area and thereforepotential capacitance by an addition ˜10×.

TABLE 1 Capacitance per Projected Area per Pillar Height. Capacitanceper Projected Area per unit Pillar Height (nF/cm²/nm) PercentCapacitance Increase of Circular Shaped Shaped Nanowire NanowireNanowire Capacitor Capacitor Capacitor Analytical 12.62 22.24 76.20%Experimental  9.67 18.44 90.62%

Various experimental methods have been employed, such as MACE,Si-Nanowire (NW) fabrication, Si-NW capacitor fabrication and SEMpreparing and imaging discussed below.

MACE

Metal Assisted Chemical Etching (MACE) is a wet etch process wheresilicon is preferentially etched at the interface between a noble metaland the silicon surface in a solution of hydrofluoric acid (HF),deionized (DI) water, and an oxidant (commonly H₂O₂). This results in ananisotropic etch where the geometry of the features is determined by theshape of the patterned noble metal as well as the metal's mechanicalstability during the etch. The preferential etch mechanism is asfollows: (i) the noble metal catalyzes the reduction of the oxidantcreating holes, (ii) the holes are injected through the metal into thesilicon where it contacts the metal, (iii) the silicon oxidizes, (iv)the HF dissolves the oxidized silicon, and (v) finally, the solubleproducts are removed and the metal moves into the space where theprocess repeats.

Si-NW Fabrication

Silicon nanowires are fabricated using the MACE process when the metalcatalyst is a continuous thin film with an array of openings. Goldmeshes with diamond holes and circular holes were fabricated using abi-layer lift-off process. First, the diamond shaped or circular shapedpillars are imprinted on a 100 nm layer of polyvinyl alcohol (PVA). Thecircular pillars have a diameter of 100 nm and a pitch of 200 nm and thediamond pillars are imprinted using the template made by the ALDprocess. After the RLT is removed, a slightly isotropic dry etch is usedto created overhangs to help with the lift-off Gold is then deposited onthe sample using an e-beam evaporator and finally, lift-off is performedin water with ultra-sonication.

Si-NW Capacitor Fabrication

ALD was used to deposit 11 nm of hafnium oxide and 50 nm of titaniumnitride on nano-pillar arrays to fabricate metal-insulator-siliconnano-capacitors. Aluminum was sputtered onto the backside of the waferto create better contact for the measurements. The sample was dividedinto 300 μm by 300 μm capacitors by using photolithography to definecontact pads for capacitance measurements.

SEM Preparation and Imaging

Samples were coated with ruthenium tetroxide by chemical vapordeposition to artificially induce contrast. Ruthenium tetroxideselectively reacts with the polymer acrylate groups allowing forenhanced visualization of structural detail. A 0.5% aqueous solution ofruthenium tetroxide was placed in a sealed container for two hours withthe SEM samples. All SEM images were taken below 2 kV with maximumworking distance of 3 mm. The diamond template was made up of a set of 9diamond grids. A gridding system was used to track particular diamondsthrough each step of the fabrication process. An image processinganalysis software was employed to analyze the resulting SEM images. TheSEM images were converted into a binary format for analysis and edgedetection was used to define the contour lines.

Another aspect of imprint lithography is the ability of the process tocreate replicas of templates—one master template can be used to create alarge number of daughters or replicas which can then be used in volumemanufacturing. It is important though to ensure that if precisenanoshapes are included in the master, they can be retained whilecreating the replica. An etch-free approach to create replicas isdescribed below as anisotropic RIE processes can cause damage to sharpshapes, a topic that is discussed later herein. FIG. 10 is a flowchartof a method 1000 for retaining the detailed shapes of an imprintedfeature while creating a replica without use of a reactive ion etch(RIE) process in accordance with an embodiment of the present invention.FIG. 10 will be discussed in conjunction with FIGS. 11A-11F which depictcross-sectional views of fabricating a replica template using the stepsdescribed in FIG. 10 in accordance with an embodiment of the presentinvention.

Referring to FIG. 10, in step 1001, a master template 1101 is used forpatterning of imprint material 1102 on a residual layer 1103 that ispositioned on a dissolvable micron-scale layer 1104 which is positionedon a substrate 1105 as shown in FIG. 11A.

In step 1002, a dielectric layer (e.g., SiO₂ or SiN) is deposited overimprint material 1102 and residual layer 1103 using atomic layerdeposition to capture shape details followed by chemical vapordeposition to create a film 1106 over imprint material 1102 and residuallayer 1103 shown in FIG. 11B.

In step 1003, a chemical-mechanical planarization process is implementedto planarize dielectric film 1106 as shown in FIG. 11C.

In step 1004, a replica substrate (e.g., glass) 1107 is bonded ontoplanarized film 1106, where the bonding can be anodic or using anadhesive that covalently bonds with planarized film 1106 and replicasubstrate 1107 as shown in FIG. 11D.

In step 1005, dissolvable layer 1104 is eliminated in a liquid bathfollowed by drying and flipping over the structure as shown in FIG. 11E.

In step 1006, the remaining imprint material 1102 is removed using anoxidizing cleaning technique, such as an oxygen plasma ash, therebyforming a replica template 1108 as shown in FIG. 11F.

Referring to FIGS. 10 and 11A-11F, the master and replica templatesubstrates 1101, 1108, respectively, may be made from glass (fusedsilica, quartz, etc.). In one embodiment, imprint material 1102 may be acommercially material, such as the MonoMat series of materials offeredby Molecular Imprints, Inc. Dissolvable layer 1104 may be a material,such as PVA (dissolves in water at ˜80° C.) or a positive photoresist.One common positive photoresist used with the I-line exposure from amercury-vapor lamp is based on a mixture of diazonaphthoquinone (DNQ)and novolac resin (a phenol formaldehyde resin). DNQ inhibits thedissolution of the novolac resin, but upon exposure to I-line, thedissolution rate increases dramatically. DNQ-novolac resists can then bedissolved in a basic solution (usually 0.26N tetramethylammoniumhydroxide (TMAH) in water). The dissolvable layer may be optionallycoated using a TranSpin or ValMat materials (commercially developed byMolecular Imprints, Inc.) to enhance compatibility with imprint material1102. The thickness of dissolvable layer 1104 is chosen to be on themicron scale (1-20 microns) to enable fast liquid phase separation ofthe sandwich shown in FIG. 11D. In FIG. 11B, imprint material 1102 maybe optionally treated with a brief exposure to O₂ plasma to createchemical reaction sites on the imprinted polymer to enhance atomic layerdeposition (ALD) on the polymer without affecting the shape control ofimprinted features 1102. The ALD may be followed by a chemical vapordeposition (CVD) process to create the film in FIG. 11B, the ALD beingprimarily important for precise shape retention and CVD allowing forfaster deposition of the dielectric. In some cases, only CVD or only ALDmight be used. The dielectric deposition might be interleaved with thedeposition of a conducting material, such as AN to facilitate in-situSEM characterization as discussed earlier. In one embodiment, theALD/CVD is carried out at temperatures below about 150° C. to ensurethat the imprinted polymer does not undergo any shape deformation. Insummary, the process steps of method 1000 provide a process forreplicating nanoshape templates while substantially retaining patternprecision.

Another aspect of the present invention is the ability to performin-situ metrology of the imprinted resist to check and qualify the shapeof the pattern after imprint, and to correlate the imprinted shape tothe master template shape. During SEM imaging, prolonged exposure to theelectron beam can deform the polymer making precise shape measurementsextremely difficult to attain. To overcome these challenges, a chemicalstaining approach was invented. A chemical vapor deposition of rutheniumtetroxide was performed to coat the nanopatterns with a thin conductivelayer. To further alleviate electron beam effects, the SEM images (shownin FIGS. 12A-12C) were taken at low keV. The staining method of thepresent invention may be very important for in-situ metrology prior totemplate replication to ensure that the replica possesses the desirednanoscale control and prior to developing etch processes as discussedbelow.

It has been discovered that etching of nanoshape features intofunctional films using imprinted polymers has some challenges. The etchprocess for imprint lithography requires two steps, the first step is anon-selective etch of the residual layer of the polymer created in theimprint step (see method 1000 of FIG. 10). This step is a pure physicaletch and has a tendency to erode sharp and nanoscale structures. Thesecond step involves a more selective etch between the imprint resistand the underlying film and is therefore somewhat less damaging ofnanoscale precision in features. There are two ideas disclosed in thepresent invention.

The first idea is to pre-compensate the template feature to create astructure which when exposed to anisotropic RIE will lead to a finalstructure that is the desired structure. This approach is likely suitedfor both steps of etch discussed above (non-selective and selectivesteps), but is particularly beneficial for the non-selective residuallayer etch step. The idea is demonstrated by the experimental resultsdiscussed below where a diamond-like shape is fabricated with very sharpnano-corners as shown in FIGS. 12A-12C.

FIG. 12A is a scanning electron microscope (SEM) image of apre-compensated template in accordance with an embodiment of the presentinvention. FIG. 12B is an SEM image of the imprinted feature with ananoscale bridge in accordance with an embodiment of the presentinvention. FIG. 12C is an SEM image of the post-etch pattern withseparated diamond-like shapes in accordance with an embodiment of thepresent invention.

Referring to FIGS. 12A-12C, a pre-compensated template (FIG. 12A)creates the imprinted pattern in FIG. 12B which includes a “nanoscalebridge” that connects adjacent diamond-like shapes. After etching (asshown in FIG. 12C), the bridge is lost leading to the desired separatednano-shaped diamonds.

The second idea is discussed in connection with FIGS. 13 and 14A-14D. Itinvolves the creation of a negative replica of the imprinted pattern ina dense inorganic material, such as SiO₂ or SiN, so that the subsequentetching of the pattern into the functional film is performed using anetch mask that is significantly more robust in RIE processes as comparedto imprinted polymers that have polymer chains on the order of the sharpshapes that are being transferred. The process can be implemented afterthe non-selective residual layer etch (as discussed in method 1300 ofFIG. 13) or prior to such a non-selective etch. In the latter case, aselective etch of the residual layer will be required after theinorganic negative pattern has been created. The “etch back” step inFIG. 13 could involve a blanket uniform etch process using a halogenchemistry for materials, such as SiO₂. The approach of method 1300 ofFIG. 13 can be combined with the first idea (pre-compensation) tofurther account for any parasitics that may result from the residuallayer etch or etch into the functional film.

FIG. 13 is a flowchart of method 1300 for creating a negative replica ofthe imprinted image in a dielectric in accordance with an embodiment ofthe present invention. FIG. 13 will be discussed below in conjunctionwith FIGS. 14A-14D which depict cross-sectional views of creating anegative replica of the imprinted image in a dielectric using the stepsdescribed in FIG. 13 in accordance with an embodiment of the presentinvention.

Referring to FIG. 13, in step 1301, a dielectric layer 1401 is depositedvia atomic layer deposition and chemical vapor deposition over imprintmaterial 1402 and residual layer 1403 as illustrated in FIG. 14A. Asfurther illustrated in FIG. 14A, residual layer 1403 is positioned abovea layer of functional film 1404 which is positioned above a substrate1405. In one embodiment, imprint material 1402 is comprised of denseinorganic material (e.g., SiO₂ or SiN).

In step 1302, a chemical-mechanical planarization of dielectric layer1401 is performed as shown in FIG. 14B.

In step 1303, the planarized dielectric layer 1401 is etched back asshown in FIG. 14C. In one embodiment, imprint material 1402 ispre-compensated (as discussed above) to account for system degradationof shape during the etching step. In one embodiment, the planarizeddielectric layer 1401 is further planarized via chemical-mechanicalplanarization after etching back the planarized dielectric layer 1401.

In step 1304, a negative pattern is created after removing imprintmaterial 1402 via oxygen plasma ashing as shown in FIG. 14D.

In this manner, the resulting negative replica is composed of a muchtighter packed inorganic material as compared to the imprinted polymer.The imprinted polymer is expected to have poorer pattern retention whenexposed to RIE gases and anisotropic physical etching in particular, ascompared to these inorganic materials. Therefore, these inorganicmaterials can be used for subsequent pattern transfer into theunderlying functional films without substantial loss of nanoscalepattern fidelity.

Another aspect of the present invention is to use the template withprecise nanoscale features to pattern an underlying film of imprintresist, which is then used to create a complementary pattern in a noblemetal, such as gold, silver, palladium, platinum, rhodium or othermetals, such as copper. In one embodiment, the precise nanoscalefeatures are patterned using Jet and Flash Imprint Lithography (J-FIL™)as it enables patterning of sub-10 nm high density features withversatile geometries over large areas. Other forms of imprintlithography can also be used in this context, such as thermally moldedpolymer nanoimprint lithography or UV cured spin-on resist basednanoimprint lithography, all with molecular-scale resolution. Afterdefining the resist pattern, a lift-off process is used to transfer thepost-JFIL resist pattern into a thin metal (e.g., gold) layer thatdefines a robust “mesh” for Metal-Assisted Chemical Etching (MACE),which is a solution based anisotropic etch technique that utilizes anoble metal, such as gold, to catalyze the chemical reaction in thesolution to significantly increase the silicon etch rate at thesilicon-metal interface. The difference in etch rate between the baresilicon and the silicon covered with a patterned metal layer means thatthe high aspect ratio features that retain the shape of the patternedmetal can be fabricated. This gold mesh is then used in the MACE processto create silicon nanowires with diamond-shaped cross sections and highaspect ratios (with values exceeding 140 demonstrated). Imprintlithography can pattern a greater variety of shapes, including squares,which would have a larger fill factor compared to circular cross sectionpillars for the same critical dimension. Various non-circular geometriescan also be used to improve the area moment of inertia, which willincrease the stiffness of the nanowires, thus allowing for higher aspectratio pillars and larger surface area to projected unit area. Forobtaining the noble metal (e.g., gold) pattern using the imprintedresist on a silicon wafer, one of three post-imprint and pre-MACEprocesses can be used, depending on whether the template prints pillarsor holes.

The first method is a bilayer lift-off based process using a templatethat prints holes in the resist with a high degree of geometric shapeprecision as discussed below in connection with FIGS. 15 and 16A-16D.FIG. 15 is a flowchart of a method 1500 for performing a bi-layerlift-off using a template that prints holes in the resist in accordancewith an embodiment of the present invention. FIG. 15 will be discussedbelow in conjunction with FIGS. 16A-16D which depict cross-sectionalviews of performing a bi-layer lift-off using a template that printsholes in the resist using the steps described in FIG. 15 in accordancewith an embodiment of the present invention.

Referring to FIG. 15, in step 1501, the wafer 1601 (e.g., silicon wafer)is spin coated with polyvinyl alcohol (PVA) 1602 (a sacrificialpolymeric layer) to act as the lift-off layer later in the process asshown in FIG. 16A.

In step 1502, a resist layer 1603 is deposited on PVA layer 1602 asshown in FIG. 16A.

In step 1503, an array of holes 1604 is patterned in resist layer 1603as shown in FIG. 16A. That is, resist layer 1603 is imprinted with ahole tone.

In step 1504, a silicon organic coating 1605, such as a Si-containingUV-curable monomer (e.g., Silspin™), is deposited so that these holes1604 are filled as shown in FIG. 16A.

In step 1505, coating 1605 is planarized and etched back to create anarray of cylinders 1606 as shown in FIGS. 16A and 16B. In oneembodiment, coating 1605 (e.g., Silspin™) is etched back by using a CHF₃and O₂ etch to create an array of Silspin™ cylinders 1606 surrounded bypolymer.

At this point, cylinders 1606 are surrounded by polymer layers (e.g.,resist 1603, PVA 1602). As a result, in step 1506, resist 1603 and PVA1602 are etched using an oxygen plasma etch to oxidize coating 1605 asshown in FIG. 16B. For example, the polymer layers can then be etched inplasma O₂ to oxidize coating 1605 (e.g., Silspin™) which acts like ahard mask for the isotropic etch of the polymer. This etch createsoverhangs essential to creating sharp edges during the gold deposition(discussed below) using PVD, for example, e-beam evaporation, to createa disconnection between the metal on top of the polymeric features andthe metal that is located at the bottom of the feature and in contactwith the silicon (1601). This disconnection facilitates lift-off. In oneembodiment, approximately ˜2 nm of titanium can be used as an adhesionlayer to avoid gold delamination during lift-off. In one embodiment,such a metal may be deposited via PVD to promote adhesion.

In step 1507, a metal 1607, such as gold, silver, platinum, rhodium,copper and palladium, is deposited on the array of cylinders 1606 asshown in FIG. 16C, such as via PVD. FIG. 16C specifically illustratesthe deposition of gold on the array of cylinders 1606.

In step 1508, PVA 1602 is lifted off with water resulting in the goldmesh 1608 shown in FIG. 16D. The resulting gold mesh 1608 fabricatedusing this bi-layer lift-off process can reproduce template features,substantially retaining the shape. The resulting nanowires fabricatedafter performing MACE thus replicate the template features.

The second method is a reverse tone bi-layer lift-off process fortemplates that print holes as discussed below in connection with FIGS.17 and 18A-18D. FIG. 17 is a flowchart of a method 1700 for performing areverse tone bi-layer lift-off process with resist pillars as opposed toholes in accordance with an embodiment of the present invention. FIG. 17will be discussed below in conjunction with FIGS. 18A-18D which depictcross-sectional views of performing a reverse tone bi-layer lift-offprocess with resist pillars using the steps described in FIG. 17 inaccordance with an embodiment of the present invention.

Referring to FIG. 17, in step 1701, the wafer 1801 (e.g., silicon wafer)is spin coated with polyvinyl alcohol (PVA) 1802 (a sacrificialpolymeric layer) to act as the lift-off layer later in the process asshown in FIG. 18A.

In step 1702, a hard mask 1803 (sacrificial inorganic layer) (e.g.,silicon dioxide (SiO₂), silicon nitride) is deposited on the film of PVA1802 coated on the silicon wafer 1801. In one embodiment, an adhesionpromoting layer of materials, such as Transpin™, is spin-coated on hardmask 1803 following which imprint lithography is carried out. Such

In step 1703, a resist layer 1804 is deposited.

In step 1704, pillars 1805 are imprinted in resist layer 1804 as shownin FIG. 18A.

In step 1705, resist layer 1804 is removed using an oxygen ashingprocess as shown in FIG. 18B.

In step 1706, the pattern is transferred into hard mask 1803 using avacuum based etch step with fluorine (F) based chemistry as shown inFIG. 18B.

In step 1707, a further etch is performed in oxygen based plasmachemistry which does not attack hard mask 1803 but undercuts PVA film1802 by isotropically etching the exposed material as shown in FIG. 18B.

In step 1708, a metal 1806, such as gold, silver, platinum, rhodium,copper and palladium, is deposited, such as via e-beam evaporation orother PVD, as shown in FIG. 18C. FIG. 18C specifically illustrates thedeposition of gold. Because of the undercut PVA film 1802, gold layer1806 is not a blanket coating, but rather a discontinuous film with goldislands on top of the hard mask pillars and a contiguous “mesh” of goldin contact with silicon wafer 1801 as shown in FIG. 18C.

In step 1709, PVA 1802 is lifted off with water resulting in the goldmesh 1807 shown in FIG. 18D. The resulting gold mesh 1807 fabricatedusing this bi-layer lift-off process can reproduce template features,substantially retaining the shape. The resulting nanowires fabricatedafter performing MACE thus replicate the template features.

The third method is a simplified bi-layer lift-off process as discussedbelow in connection with FIGS. 19 and 20A-20D. FIG. 19 is a flowchart ofa method 1900 for performing a simplified bi-layer lift-off processwhere the SiO₂ hard mask is not used and the selectivity between theimprint resist and PVA only needs one polymer etch to create asufficient overhang for the gold deposition in accordance with anembodiment of the present invention. FIG. 19 will be discussed below inconjunction with FIGS. 20A-20D which depict cross-sectional views ofperforming a simplified bi-layer lift-off process using the stepsdescribed in FIG. 19 in accordance with an embodiment of the presentinvention.

Referring to FIG. 19, in step 1901, the wafer 2001 (e.g., silicon wafer)is spin coated with polyvinyl alcohol (PVA) 2002 (a sacrificialpolymeric layer) to act as the lift-off layer later in the process asshown in FIG. 20A.

In step 1902, a resist layer 2003 is deposited.

In step 1903, pillars 2004 are imprinted in resist layer 2003 as shownin FIG. 20A.

In step 1904, an etch is performed to remove the residual layerthickness and to isotropically etch PVA layer 2002 as shown in FIG. 20B.

In step 1905, a metal 2005, such as gold, silver, platinum, rhodium,copper and palladium, is deposited, such as via e-beam evaporation orother PVD, as shown in FIG. 20C. FIG. 20C specifically illustrates thedeposition of gold. Because of the undercut PVA film 2002, gold layer2005 is not a blanket coating, but rather a discontinuous film with goldislands on top of the hard mask pillars and a contiguous “mesh” of goldin contact with silicon wafer 2001 as shown in FIG. 20C.

In step 1906, PVA 2002 is lifted off with water resulting in the goldmesh 2006 shown in FIG. 20D. The resulting gold mesh 2006 fabricatedusing this bi-layer lift-off process can reproduce template features,substantially retaining the cross-section shape. The resulting nanowiresfabricated after performing MACE thus replicate the template features.

The results of method 1900 are shown below in FIGS. 21, 22A-22B, 23 and24A-24B. FIG. 21 illustrates the gold mesh with circular holes createdusing method 1900 in accordance with an embodiment of the presentinvention, where the scale bar is 200 nanometers.

FIG. 22A illustrates the top down SEM of the pillars etched using thesimplified circular mesh in accordance with an embodiment of the presentinvention, where the scale bar is 1 micrometer.

FIG. 22B illustrates the cross-section of the SEM of the pillars etchedusing the simplified circular mesh in accordance with an embodiment ofthe present invention, where the scale bar is 200 nanometers.

FIG. 23 illustrates the gold mesh with diamond holes created usingmethod 1900 in accordance with an embodiment of the present invention,where the scale bar is 200 nanometers.

FIG. 24A illustrates the top down SEM of the pillars etched using thesimplified diamond mesh in accordance with an embodiment of the presentinvention, where the scale bar is 100 nanometers.

FIG. 24B illustrates the cross-section of the SEM of the pillars etchedusing the simplified diamond mesh in accordance with an embodiment ofthe present invention, where the scale bar is 200 nanometers.

An exemplary application using ultracapacitors is discussed below inconnection with FIGS. 25 and 26A-26E.

FIG. 25 is a flowchart of a method 2500 for fabricating anultra-capacitor from nanowires in accordance with an embodiment of thepresent invention. FIG. 25 will be discussed below in conjunction withFIGS. 26A-26E which depict cross-sectional views of fabricating anultra-capacitor from nanowires using the steps described in FIG. 25 inaccordance with an embodiment of the present invention.

Referring to FIG. 25, in step 2501, a dielectric 2602 is deposited onsilicon nanopillars 2601 as shown in FIGS. 26A-26B. For example, in oneembodiment, approximately 11 nm of hafnium dioxide, the dielectric 2602,is deposited using atomic layer deposition (ALD).

In step 2502, the gaps are filled with titanium nitride 2603 to be thesecond electrode as shown in FIG. 26C. In one embodiment, the gaps arefilled with 50 nm of titanium nitride to be the second electrode.

In step 2503, aluminum 2604 is sputtered onto the backside of the waferas shown in FIG. 26D. Aluminum was sputtered onto the backside of thewafer to create a better contact for the measurements.

In step 2504, samples of capacitors are defined using photolithographyand wet etch as shown in FIG. 26E. In one embodiment, the sample wasdivided into 300 μm by 300 μm capacitors by using photolithography todefine separate samples for testing with a CV probe station. In general,silicon nanoshapes can enable important applications in energy,healthcare and electronics, such as nanowire sensors for gaseous,biological and chemical species detection, battery anodes,ultra-capacitors, thermoelectrics, nanowire FETs and nanoantennae. Thelarge surface area to volume ratio (large surface areas per unitprojected area) of shaped nanopillars can improve critical properties,such as sensor sensitivity, capacitor and battery storage capacity.Shaped nanopillars can be tailored to have greater effective surfacearea as compared to their cylindrical counterparts.

If necessary, nanowires can also be harvested after MACE processing bypouring a PolyDimethylsiloxane (PDMS) mold onto the substrate, curingthe PDMS, peeling the PDMS layer off, dissolving the PDMS, andseparating out the nanowires with either filtration or chemicalseparation. Peeling the PDMS layer off can be done by sonicating thewafer or by mechanically initiating a crack at the PDMS/substrateinterface at the edge of the substrate with a thin blade and followingthe crack propagation with the edge of the blade. With enough shearforce and bending moment applied to the base of the nanowires duringpeel-off by either the blade or the sonication process, the nanowirescan be detached from the substrate and retained within the PDMS mold.That is, nanowires may be sheared form the wafer using mechanical oracoustic forces. If the gold mesh remains in good fidelity after peeloff, the silicon substrate can be used again for subsequent MACEprocesses. Any excess PDMS on the silicon surface can be cleaned usingwet chemistries involving appropriate solvents or Piranha solution.Thus, one silicon wafer can theoretically be processed several times inthis way to produce nanowires. The nanowires can be collected insolution and either stored as colloids or isolated as a powder byevaporating the solvent medium.

The descriptions of the various embodiments of the present inventionhave been presented for purposes of illustration, but are not intendedto be exhaustive or limited to the embodiments disclosed. Manymodifications and variations will be apparent to those of ordinary skillin the art without departing from the scope and spirit of the describedembodiments. The terminology used herein was chosen to best explain theprinciples of the embodiments, the practical application or technicalimprovement over technologies found in the marketplace, or to enableothers of ordinary skill in the art to understand the embodimentsdisclosed herein.

The invention claimed is:
 1. A method for template fabrication ofultra-precise nanoscale shapes, the method comprising: formingstructures with a smooth shape on a substrate using lithography;subjecting said structures to an atomic layer deposition of one or morefilms leading to nanoscale sharp shapes with features that exceedlithography resolution capability of sub-10 nm resolution; performing aresist imprint of said nanoscale sharp shapes using imprint lithography;and etching said nanoscale sharp shapes into underlying functional filmson said substrate forming a nanoshaped template with nanoscale sharpshapes that comprise one or more of the following: sharp corners andultra-small gaps ranging from 1 to 10 nanometers.
 2. The method asrecited in claim 1, wherein said structures comprise circular orelliptical cross-section pillars.
 3. The method as recited in claim 1,wherein said substrate comprises a fused silica substrate.
 4. The methodas recited in claim 1, wherein said underlying functional films comprisethermal oxide.
 5. The method as recited in claim 1, wherein saidnanoscale sharp shapes are diamond-like shapes.
 6. The method as recitedin claim 1, wherein said nanoshaped template with nanoscale sharp shapesis utilized in magnetic memory, nanophotonic devices or biomedicalapplications.
 7. The method as recited in claim 1, wherein saidlithography comprises one of the following: electron beam lithography,ion beam lithography and multiphoton lithography.
 8. The method asrecited in claim 1, wherein said one or more films comprises adielectric interleaved with a deposition of a conductive film.
 9. Themethod as recited in claim 1, wherein said imprint lithography comprisesJet and Flash Imprint Lithography (J-FIL).
 10. The method as recited inclaim 1, wherein said one or more films comprise two or more filmscomprising a dielectric and a conducting film.
 11. The method as recitedin claim 10, wherein said dielectric comprises one of the following:silicon dioxide and silicon nitride, wherein said conducting filmcomprises titanium nitride.
 12. The method as recited in claim 1,wherein said nanoshaped template is pre-compensated to account forpattern degradation of shape during said etching.
 13. The method asrecited in claim 12, wherein said nanoshaped template is pre-compensatedby using a nanoscale bridge that connects adjacent nanoscale sharpshapes.
 14. A method for template replication of ultra-precise nanoscaleshapes, the method comprising: using a master template for patterning ofimprint material on a residual layer that is positioned on a dissolvablelayer which is positioned on a substrate; depositing a dielectric layerover said imprint material and said residual layer to capture shapedetails; performing one of chemical vapor deposition, physical vapordeposition and atomic layer deposition of said deposited dielectriclayer to create a film over said imprint material and said residuallayer; planarizing said film; bonding a replica substrate onto saidplanarized film; eliminating said dissolvable layer followed by flippingover a structure comprising said imprint material, said residual layerand said substrate; and removing said imprint material thereby forming areplica template.
 15. The method as recited in claim 14, wherein saiddissolvable layer has a thickness between 1 and 20 micrometers.
 16. Themethod as recited in claim 14, wherein said imprint material is removedusing an oxidizing cleaning technique.
 17. The method as recited inclaim 14, wherein said dissolvable layer is eliminated in a liquid bath.18. The method as recited in claim 17 further comprising: drying saidstructure comprising said imprint material, said residual layer and saidsubstrate after eliminating said dissolvable layer in said liquid bath.19. A method to fabricate shaped cross-section silicon nanowires, themethod comprising: depositing a sacrificial polymeric layer on asilicon; imprinting on said sacrificial polymeric layer using ananoscale shaped template; etching a polymeric residual layer resultingfrom said imprinting; etching an underlying sacrificial polymeric layerfollowing said etching of said polymeric residual layer, wherein saidunderlying sacrificial polymeric layer etch results in an undercut;performing a physical vapor deposition of a metal; removing saidsacrificial polymeric layer to create nanoshaped metal structures onsaid silicon; and performing a metal assisted chemical etching processto create nanowires.
 20. The method as recited in claim 19, wherein saidmetal comprises one of the following: gold, silver, platinum, rhodium,copper and palladium.
 21. The method as recited in claim 19, wherein across-section of said nanoshaped metal structures allows for enhancedsurface area of said silicon per unit projected area of said silicon.22. The method as recited in claim 19 further comprising: depositing asacrificial inorganic layer between said sacrificial polymeric layer andsaid polymeric residual layer.
 23. The method as recited in claim 22,wherein said sacrificial inorganic layer comprises one of the following:silicon dioxide and silicon nitride.
 24. The method as recited in claim19, wherein said nanowires are harvested by casting said nanowires in apolymer and shearing said nanowires from a wafer.
 25. The method asrecited in claim 24, wherein said shearing of said nanowires isperformed using mechanical or acoustic forces.
 26. A method to fabricateshaped cross-section silicon nanowires, the method comprising:depositing a sacrificial polymeric layer on a silicon; imprinting onsaid sacrificial polymeric layer using a nanoscale shaped template;coating said sacrificial polymeric layer with a silicon organic coating;planarizing and etching said silicon organic coating in a plasmainvolving fluorine and oxygen; etching an underlying sacrificialpolymeric layer, wherein said underlying sacrificial polymeric layeretch results in an undercut; performing a physical vapor deposition of ametal to promote adhesion; performing a physical vapor deposition of asecond metal; removing said sacrificial polymeric layer to createnanoshaped metal structures on said silicon; and performing a metalassisted chemical etching process to create nanowires.
 27. The method asrecited in claim 26, wherein said second metal comprises one of thefollowing: gold, silver, platinum, rhodium, copper and palladium. 28.The method as recited in claim 26, wherein a cross-section of saidnanoshaped metal structures allows for enhanced surface area of saidsilicon per unit projected area of said silicon.
 29. The method asrecited in claim 26, wherein said nanowires are harvested by castingsaid nanowires in a polymer and shearing said nanowires from a wafer.30. The method as recited in claim 29, wherein said shearing of saidnanowires is performed using mechanical or acoustic forces.